The invention relates generally to non-destructive evaluation (NDE) and more particularly, to non-destructive evaluation of an object using ultrasound.
A variety of NDE inspection modalities are available to inspect industrial components. These inspection modalities have their own advantages and limitations and are typically employed based on the type of components that needs to be inspected. For example, ultrasound (UT) inspection is widely employed for identifying delamination.
However, in certain applications, UT inspection sometimes over-estimates defect sizes leading to false calls. Such inaccurate inspection results are prominent when objects being inspected have anisotropic material properties, are made of multi-material (e.g., glue, plys and so forth), and have thick cross-sections. Differences in the speed of sound in a component with respect to the X, Y and Z axes due to anisotropic material properties and/or the internal structure of the component causes distortion to the sound beam. Moreover, certain probe orientations (e.g., tilted relative to the part being inspected) causes additional distortion with a circular beam at the front surface becoming oval. The operator measures the dimension of the indication (defect) and will reject the component if the size of the defect exceeds a predetermined threshold. However, for anisotropic components, an indication in an image may not be representative of the real size, shape, and/or location of the defect, thereby leading to false rejections. The false rejections, in turn, can lead to increased cost and potential revenue loss.
For example, UT inspection of composite materials can provide inaccurate results, since composite materials are fibrous and inhomogeneous. The characterization of defects (size, shape, and/or location of the defect) in thick composite objects via UT inspection is challenging due to the interaction of sound with the fiber matrix. Current approaches for composite UT inspection include using a universal amplitude threshold for UT data and comparing the indication depth and location with known defect inserts. Defect characterization is typically conducted on 2D UT C-Scans. However, these techniques may not provide accurate inspection results. Further, different UT scans looking at the same defect are not correlated. Other available inspection modalities and techniques also provide limited accuracy for inspecting components made of composite material. Although composite inspection is a relatively new area, there is a need for accurate inspection of composite materials due to the increasing use of composite materials.
It would therefore be desirable to provide a technique to obtain and accurately determine indication size, shape and/or location for UT inspection of anisotropic or composite material.